It is desirable that a condom be held firmly and comfortably in place during use. Natural rubber or synthetic elastomer condoms, because they are highly elastic, are made smaller than the erect penis. These condoms are designed to stretch slightly when put on, and to contract firmly around the penis while being worn. The condom is held in place in this way during intercourse. These condoms are satisfactory in strength and thinness, and can be economically manufactured. However, they are notably inferior in sensitivity, are water impermeable, and are ineffective heat conductors. The elastic material relied upon to keep the condom in place often results in discomfort, is unduly dependent on the size of the penis, is known to become brittle, tear or fail during use more often than other types of condoms, and may deteriorate in the presence of commonly used petroleum-based lubricants.
Condoms made from natural membranes, such as lamb cecum, are satisfactory in strength and thinness, and offer improved sensitivity, permeability, and comfort. These condoms are virtually inelastic, and therefore must be made somewhat larger than the erect penis. To hold the condom in place, a slit is cut on each side of the open end of the condom, forming two flaps which can be folded down over an elastic band and glued in place. This simple gluing process can be used because the membrane is dry, and because it is supple due to the plasticizing effect of naturally occurring fat. Thus, the condom is held in place by an elastic band having a circumference adapted to contract around the penis, and not by contraction of the condom body.
In one banding method, the dry tubular cecum is placed mitten-like over a wide flat form, which flattens the condom. Starting at the top open end of the condom, slits about one-half inch long are cut on each side of the flattened membrane, making two flaps. A rubber band is place over each cecum and is positioned just below, or at the apex, of the slits. Glue is applied in a stripe to both sides of the flattened condom. The flaps are folded over the rubber band and pressed into the glue. When the glue is dry, the condom is removed from the form and is wetted prior to subsequent processing.
This banding method requires that each condom be individually handled, and there is a high risk that incipient tears at the apex of the condom, at or near the slits, will occur during processing. In addition, natural ceca are limited in availability and cecum condoms are expensive to manufacture. The final product also suffers from unavoidable surface irregularities which remain after processing of the thin natural membranes.
Efforts to develop condoms having the desirable strength and comfort characteristics of ceca-based products, but at a lower cost and without dependence on a natural resource of increasing rarity, have led to the development of collagen-based condoms, made from collagen gels. Homogeneous collagen gels capable of forming smooth films of uniform strength, and suitable for use as a condom material, are disclosed in applicant's U.S. Pat. No. 4,626,286, the subject matter of which is incorporated herein by reference. Collagen condoms and methods for manufacturing them are also disclosed in U.S. Pat. No. 4,406,853 and No. 4,349,026.
Thin film articles made from collagen gels have superior breaking and tear strength, and improved homogeneity, thinness, smoothness, sensitivity and appearance. They are also convenient and economical to manufacture.
Collagen condoms are formed by repeatedly dipping a phallic mandrel into an aqueous collagen gel, withdrawing the mandrel and drying the resulting coating. The dipping process is repeated until a collagen film having the desired thickness is obtained. In one embodiment, the mandrel may be rotated in two directions, to achieve a film that is uniformly strong in both directions.
Collagen condoms must be moist in order to readily remove them from the dipping mandrel, and they remain moist throughout subsequent processing and sale.
Collagen condoms are inelastic, like those made from ceca, and they are made larger than the erect penis. A reliable means of holding the condom in place during use is therefore needed, but the known banding means have been unsatisfactory. Glue cannot be applied to the collagen condom while it is wet. When dry, the condom material tends to be brittle, because the regenerated collagen film contains no fat. Efforts to slit and fold the dry brittle film for the known gluing process often result in tears and fractures in the condom. To delicately remove each condom from its mandrel while dry, and glue each band in place individually according to the known method, followed by a rewetting step for processing, is difficult and costly. Collagen condoms also cannot be banded merely by rolling the top of the condom before curing, using the techniques heretofore employed for banding latex condoms.
These problems and disadvantages have been overcome, according to the present invention, by advantageously incorporating an elastic banding means into the condom during the dipping process.